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by yunong 4805 days ago
Do you have any benchmarks to support your claim? Statements such as "Btrfs ... might currently be a better alternative" without benchmarks are worthless. Anyway -- I'd be interested to see benchmarks of Btrfs on GNU/Linux vs ZFS on illumos -- I suspect that ZFS "might currently be a better alternative".

Simply ratcheting off a set of features and stating that Btrfs is "better" is dubious at best, and perhaps mis-leading. As the OP stated in his blog post, ZFS has a rich feature set -- which we find invaluable in our own postgres stack -- features such as incremental snapshots, a real copy on write filesystem, etc.
1 comments
fsiefken 4805 days ago
You are half right. There are no direct and current benchmarks, but following the news through the years about Ext4, Reiser4, ZFS and Btfrs (and experimenting with them) I know the latter is quite fast disk I/O wise (again this is just a hint), I listed the alternative filesystems which support transparent compression for a future benchmark or evaluation for people - like me - who think transparent compression is a nice idea for speeding up queries.

I found 2 recent Phoronix benchmarks which compare Btfrs with Ext4 and Ext4 with ZFS respectively. You can't really combine them as it seems the hardware used is different but if you use Ext4 as a rough translation key it seems ZFS on linux (which is what the OP used) is slower then Ext4 and Btfrs. Transparent compression speed would depend on cpu and is comparable.

April 18, 2013 Ext4 vs ZFS http://www.phoronix.com/scan.php?page=news_item&px=MTM1N...

February 18, 2013 Btfrs (and others) vs Ext4 http://www.phoronix.com/scan.php?page=article&item=linux...

Unreliable Mashup which gives some indication: * fs-walk 1000 files 1 mb zfs 46.20 ext4 72.50 vs 78.67 btfrs 66.37 btfrs

* fs-walk 5000 files 1 mb 4 threads zfs 25.63 files/s ext4 79.73 vs 99.60 btfrs 94.63

* fs-mark 4000 files 32 subdir 1 mb zfs 7.78 ext4 74.07 vs 78.80 btfrs 65.17

* dbench 1 client count zfs 27.29 MB/s ext4 167.29 MB/s vs 195.24 btfrs 165.37

I'm also interested in a Btfrs benchmark vs ZFS on Illumos, this way you can determine which is the best or fastest system for this specific scenario (even thought the OP used Linux).

Incremental snaphots is a nice feature for a Postgresql stack, what is the significant or as you put it 'real' difference between the CoW and snapshot functionality of Btfrs compared to ZFS? Are there things you cannot do with Btfrs in a Postgresql stack compared to ZFS?

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